Subsequent Prescribing of New Drugs

5May 2010

Phase 3 clinical trials are critical to new drug development because they help to secure regulatory approval for the new drugs and add to the general medical knowledge base. The published results from these clinical trials are important in the adoption of new drugs; key results relating to a new drug’s safety and efficacy appear in scholarly journals and are presented at professional meetings. Scant quantitative research exists, however, on how physician participation in new drug clinical studies may influence their subsequent prescribing behavior. This research examines whether physicians who take part in phase 3 clinical trials of a new drug are more likely to prescribe that drug after it comes to market.

Few papers have measured how participation in clinical trials of any type may affect study drug prescribing. In one such case, a Dutch study of one hospital determined that the hospital’s participation in either a drug’s phase 2 or phase 3 clinical trial was associated with a 100% adoption rate of the studied drugs by the hospital’s formulary. In another study, the use ( TAP) was greater in a teaching hospital that had undertaken clinical trials of this agent.

More recently, Majumdar and colleagues attempted to assess the subsequent prescribing impact of participation in clinical trials. They concluded that the effect, if it was present at all, was small. However, they identified the major limitations to their study. The results applied to the hospital level, not to the individual physician level, and they were reported for all prescriptions within a drug class because drug-specific prescribing data were not available.

The literature is also limited in terms of the demographics, practice characteristics, and prescribing patterns of physicians of any type who adopt drugs early on. The few studies that have been published suggest that the following categories of physicians tend to be early adopters of new drugs:

younger physicians

male physicians

board-certified physicians

graduates of newer medical schools

Other studies have examined the influences on decision-making within the general physician populations in prescribing new drugs. Despite physicians’ perceptions, the research highlighted the fact that peer-reviewed academic sources of information about new drugs are of limited importance in their prescribing behaviors. Physicians also appear to place limited value on pharmaceutical marketing and Continuing Medical Education (CME) as important sources of information. More recent studies, however, have asserted that pharmaceutical information sources, such as sales forces and CME programs, may have a greater influence on actual prescribing behavior than many physicians wish to acknowledge.canadian pharmacy online

For more than 50 years, the literature emphasized the function of medical peers in influencing how physicians prescribe drugs. The newer literature highlights the role that clinical trial investigators in particular have on a local level in terms of the patterns of practice of other physicians as follows:

Rogers’ seminal work on the “diffusion of innovations” theory highlighted, among other factors, the role of peer opinion leaders in the acceptance of new ideas in a wide variety of settings. Regardless of whatever information is broadcast, published, or otherwise disseminated among a large population, most people look to the ideas of peers whose opinions are widely respected by others in the community before they accept the new idea. The same dynamic may well be at work in the acceptance of new drugs, regardless of the individual drug’s therapeutic novelty.

Using individual physician drug-specific prescribing data, the study addresses, in a matched case-control design, whether physicians’ involvement in phase 3 clinical studies affects their subsequent prescribing behavior of the study drug, particularly if that study involves a first-in-class drug. We compared the prescribing behaviors of the two groups of physicians—phase 3 clinical investigators and a matched set of control (non-investigator) physicians—three months before the start of their participation in a specific phase 3 clinical trial, and at three, six, and 18 months after the launch of the study drug.